Experiments
Experiment One In our first experiment, we are studying the impact of friction and drag on simple harmonic motion. While examining friction, we are studying how the mass and surface area of an object affect its motion as it oscillates over different materials, propelled by a spring. We are trying to determine if changing the surface area but not the mass of an object will affect its kinetic friction coefficient and therefore its motion. Experiment Two Experiment Two consist of testing how the drag forces affects a mass on a spring. This is being conducted by seeint how a mass on the spring moves in water versus how it would move on a table. Objective In my experiment, I was interested in studying the affect of the environment had on the motion of the spring in the mass, so I was studying the drag force. The drag force is a force opposite of the motion, but proportional to the speed. An example of the drag force would be air or water resistance. When designing my experiment I wanted to eliminate, as much as I could, friction with other surfaces, so my mass on a spring was vertical rather than horizontal. I put the mass on a spring over a table into a fish tank so I could replicate the experiment easily with the water. Trial and Error At first, I attempted to study simple harmonic motion horizontally by using a slinky as the spring and a glass mason jar with a handle for my mass. I cut a small part of the slinky and taped it to the side of the fish tank. I then attached the mason jar by threading a part of the slinky around the handle. I then placed a ruler next to the mason jar. I began to move the jar one inch at a time and found that the jar did not begin to move until the seven inches. However, it only moved slightly and there was a scraping sound when it did move this. This was mostly likely because there were parts of the sand stuck to the bottom of the tank. When I moved it to ten inches the jar would slid all the way back to the side of the tank and run into it. Once it hit the side of the tank it did not oscillate, or move back and forth. It also continually made the scraping noise. To try to create less friction I added soap to the bottom of the tank, but that did not work. Most likely because it made the sand adhere to the bottom of the jar. I concluded that the mass was too heavy for the spring, and that conducting the experiment horizontally would not be the best method because there was too much friction between the mass and the surface. The amount the mass moved also varied and I did not think that it was the most reliable way to conduct the experiment. Experiment Design After my first attempt, I looked at a variety of different springs before picking one that was able to stretched enough so that it would move with the mass, but not hit the bottom of the tank. I also used four magnets for my mass. Together they weighed 25 grams and were easily attachable to the spring. Then I placed a small plank of wood with a hook in it, over the table and placed a paint can on top of it to stabilize it. Then I placed the ruler vertically behind the spring so I could measure its placement. First I measured the length of the spring without any mass attached to it( Photo 1). Then I measured the length of spring with the mass to see how far it stretched(Photo 2), this data is use to the find the spring constant, K, and it is also the equilibrium point. To test out what would happen, I pulled the mass down at varying lengths. When pulled down, almost to the bottom, the oscillating motion was unpredictable and even sprung off the hook. However, when pulled down only a few centimeters it became more controlled and was very clear to see the oscillating movement. Then I used the camera on my IPhone to film, in slow motion, what happened when pulled down a few centimeters( Video 1). Then I filled the tank with cold water until the mass was submerged (Photo 3 ). I then pulled the mass down a few centimeters and filmed it again. (Video 2). Most of my procedure worked well, but I wished I had put a stopwatch in the video as well because it was difficult calculating the time of each frame in the videos. It was also difficult to read the measurements in the video I had taken.